With development of technologies, high bandwidth promised by a Long Term Evolution (Long Term Evolution, “LTE” for short) network brings a great opportunity for mobile bandwidth growth. Compared with an LTE data service, voice over LTE (Voice Over LTE, “VoLTE” for short) raises a higher requirement on wireless coverage resources, mainly because VoLTE requires higher quality-of-service (Quality-of-Service, QoS), and has a lower delay tolerance. In addition, VoLTE supports high-definition audio and video encoding and decoding, which means that VolTE has a higher bandwidth requirement, bandwidth usage of VoLTE needs to be preferably guaranteed by LTE resources scheduling. For the foregoing reasons, a growth in VoLTE subscriber base means coverage shrinkage of an LTE cell, thereby increasing cell congestion and resulting in phenomena such as call drops or blocked calls.